IXL | Find all the factor pairs of a number up to 100

Find all the factor pairs for 16 and complete the equations. Each equation should use a different pair of factors.

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question

Find all the factor pairs for 87 and complete the equations. Each equation should use a different pair of factors.

key idea

A factor of a number divides the number evenly.

A factor pair for a number is a pair of factors whose product is that number. For example, 2 and 5 are a factor pair for 10 because

You can use these divisibility rules to help find factors:

Every number is divisible by 1 and itself.
Even numbers are divisible by 2.
A number is divisible by 3 if the sum of its digits is divisible by 3.
A number is divisible by 5 if its last digit is 0 or 5.
A number is divisible by 6 if it is divisible by both 2 and 3.

solution

In the first equation, one of the factors is 87. You can use a multiplication fact to find the missing factor.

So, 1 and 87 are a factor pair for 87.

In the second equation, both factors are missing. Find one of the factors by starting with small numbers and checking whether they are factors of 87. Use divisibility rules when you can.

The digits in 87 add up to 15, which is divisible by 3. This means 87 is divisible by 3, too. So, 3 is a factor of 87.

Divide 87 by 3 to find the other factor.

So, 3 and 29 are a factor pair for 87.

These equations show all the factor pairs for 87:

Looking for more? Try these:

Lesson: Factors

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Complete the factor pairs of a number

Lesson: Factors

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